The present invention, in some embodiments thereof, relates to a card-based mounting assembly and maintenance system, more particularly but not exclusively to a backplane or the like which supports cards, and, more particularly, but not exclusively, to communications equipment based on such an assembly.
A backplane is a circuit board, usually a printed circuit board that connects several connectors in parallel to each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete computer system.
Backplanes are normally used in preference to cables because of their greater reliability. In a cabled system, the cables need to be flexed every time that a card is added to or removed from the system; and this flexing eventually causes mechanical failures. A backplane does not suffer from this problem, so its service life is limited only by the longevity of its connectors. For example, the DIN 41612 connectors used in the VMEbus system can withstand 50 to 500 insertions and removals (called mating cycles), depending on their quality.
Backplanes have also become commonplace for communications switches including telephone exchanges, as well as disk enclosures, disk arrays, and servers. A problem with telephone exchanges, particularly the local exchange, is that these are dispersed geographically to be near or around the various premises to which the telephone services are provided. Maintenance, of even the most trivial nature, typically requires an engineer to be sent on site.
It is highly desirable to automate maintenance of such backplane based switching systems, so as to save on the need to call out the engineer. However a difficulty arises in that much in the way of modern communication traffic passes via optical fiber. Backplanes today do not include optical connectors and the cards fitted onto the backplane need to have separate connectors for any optical connections. These connectors need to be removed when cards are replaced in maintenance operations. Removing the optical connectors requires manual intervention, and thus it is not possible for the maintenance operation to be automated.
U.S. Pat. No. 7,418,165 teaches a flexible optical connector suitable for use in an optical backplane for interconnecting optical circuit boards, and methods of making the optical connector. The flexible optical connector comprises a plurality of waveguides on two or more levels providing a plurality of light paths that allow light communication between optical circuit boards. The optical connector can be manufactured separately from the backplane and thereafter mounted on the backplane. The backplane may also have a mounting structure for removably retaining and positioning the optical circuit board and may, optionally, include electrical traces for providing electrical interconnections between the circuit boards. The backplane provided however is not optimized for allowing automatic maintenance.